Boy George has talked of his fears of a growing intolerance towards people who stand out from the norm after his close friend Philip Sallon was attacked in central London following a night out.

Sallon, 59, known for his outrageous sense of style, remained in hospital on Friday with a fractured skull and broken bones after being attacked in the early hours of last Saturday.

He was found unconscious by paramedics in Shaftesbury Avenue at around 3.30am, after a witness called 999 before leaving the scene.

No witnesses have come forward and no CCTV footage of the attack outside the Gap store in Piccadilly Circus has been uncovered by police, who say there is as yet no evidence to suggest it was a homophobic attack. Police said in a statement: "The victim was outside the Gap store at approximately 03:30 hours when officers believe he was approached by two suspects who kicked him repeatedly in the head and subsequently ran off."

But Boy George, real name George O'Dowd, said there were few other likely motivations. "It's hard to say and you don't want to jump to conclusions, but it must have been something to do with the way he looked," he said. "I can't think of any other reason. Philip is not a bruiser."

The singer described Sallon – who founded the Mud Club in Tottenham Court Road in the 1980s – as his "oldest friend", whom he had known since he was 15.

Sallon is well known for his style and outgoing personality. Admirers describe how during one club night in the 1980s he wore a dress made entirely of pound notes; by the end of the evening, after fellow clubbers had helped themselves, he was practically naked.

But George said he felt that attitudes towards overt individuality had hardened since the 80s. "These things go in circles," he said. "In the early 80s there was this sense that things were changing, and becoming more open-minded. But we don't have that sort of gorgeous youth culture any more, the glam rockers, the New Romantics. People aren't so individual any more. There is this sense of why would you want to stand out and make a show of yourself?"

He added: "You can find that sort of attitude in the gay community too. That if you are an exhibitionist you are somehow spoiling the big assimilation. Most gay men go out of their way to look normal and fit in, but Philip is not of that breed." Despite shifts in public attitudes towards homosexuality, much more progress still had to be made, George said. "Just because you see a few more gay people on TV doesn't mean there is no longer a problem. In the last 10 years we have seen lots of attacks in the West End, people have been killed. [Homosexuals being targeted] is not uncommon."

George was angry at police who have so far found no CCTV footage of the attack. "This is an area that we are told is a terrorist hotspot, with cameras everywhere and yet there is no footage – it just seems so unlikely," he said. "This wasn't a squabble, he was kicked repeatedly in the face, he could have been killed and he is still not out of danger."

In a statement the Metropolitan police said the attack was being investigated by the Westminster serious violence team, but was not being treated as a homophobic crime.

Miriam Elia, Sallon's niece, appealed for witnesses. "It was in the middle of central London – someone must have seen something," she said.

The West End has seen an increase in homophobic attacks in the past 12 months, according to the Met. While overall homophobic crime dropped by 3% in the capital from 2009-10 to 2010-11, in Westminster, which contains the West End and Soho, there was a 20.9% increase – from 115 to 139 – in the 12 months to February compared with the same period a year earlier. In January a teenager was jailed for seven years for a savage and fatal homophobic attack in Trafalgar Square.